DETERMINANTS OF SENSITIVITY TO 1-BETA-D-ARABINOFURANOSYLCYTOSINE IN HCT-116 AND NCI-H630 HUMAN COLON-CARCINOMA CELLS

作者：GREM JL^*; GEOFFROY F; POLITI PM; CUDDY DP; ROSS DD; NGUYEN D; STEINBERG SM; ALLEGRA CJ

来源：Molecular Pharmacology, 1995, 48(2): 305-315.

The cytotoxicity and metabolism of 1-beta-D-arabinofuranosylcytosine (AraC) and its effects on DNA synthesis and integrity were studied in HCT 116 and NCl-H630 human colon cancer cells. In 116 cells, 0.1 mu M AraC decreased colony formation by similar to 50%, whereas 1 mu M was required in H630 cells. AraCTP levels after a 24-hr AraC exposure were 2.3- to 3.5-foId lower in H630 cells due to increased ability to deaminate AraCMP. AraC DNA levels increased in proportion to AraCTP pools (r = 0.99) and were 2-fold higher in 116 cells after a 24-hr exposure to 0.1 and 1 mu M AraC. Although the half-life of AraCTP was < 1 hr in both lines, > 80% of AraC DNA was retained at 24 hr after drug removal. Clonogenic capacity was inversely related to the extent of AraC DNA incorporation. Interference with nascent DNA chain elongation increased with increasing AraC concentration x time. A 24-hr AraC exposure produced a dramatic shift in the elution profile of nascent DNA during a 15-hr elution at pH 12.1; these effects were greater in 116 cells (DNA retained on filter [percentage of control]): 78%, 23%, and 9% with 0.1, 1, and 10 mu M AraC versus 84%, 42%, and 18% in H630 cells, respectively. The extent of nascent DNA damage was proportional to AraC DNA content. Net DNA synthesis was potently inhibited during AraC exposure in both lines. H630 cells had partial recovery of DNA synthesis at 24 hr after drug removal, whereas persistent inhibition was noted in 116 cells. A slight excess of double-strand breaks in parental DNA was detected after a 24-hr exposure to 10 mu M AraC in 116 cells. The extent of DNA fragmentation was more pronounced 16 hr after drug removal and was greater in 116 cells: 8.5%, 19%, and 21% with 0.1, 1, and 10 mu M AraC versus 2.3%, 9%, and 15% in 630 cells, respectively. Thus, AraC DNA content, magnitude of nascent DNA damage, duration of DNA synthetic inhibition, and induction of double-stranded DNA fragmenation appeared to be the crucial determinants of lethality.

• 出版日期1995-8